Bake oven for incandescent lamps



July 21, 1953 A. w. HOLZER BAKE OVEN FOR INCANDESCENT LAMPS 2 Sheets-Sheet 1 Filed Sept. 22, 1951 I INVENTOR 4. m #01 Z67? July 21, 1953 A. w. HOLZER BAKE OVEN FOR INCANDESCENT LAMPS 2 Sheefs-Sheet 2 Filed Sept. 22, l 951 INVENTOR aha/ 0425K avg ATTORNEY Patented July 21, 1953 Albert-W. Holzer, Arlington, N. J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 22, 1951, Serial No. 247,890

1 This'invention relates to ovens and, more particularly, to a baking oven for curing the varnish 2 Claims. (01. 34-405) seal between the bases and the envelopes of miniature lamps.

A sealed package unit foruse as an automotive. light source comprises a generally parabolic refiector sealed to a lens at one end and soldered to the base shell of a minature automotive lamp at the other end. The lamp for a sealed package unit has the conventional vitreous envelope, a filament mount sealed .to the neck of said envelope, and a base cemented to the sealed end of said envelope. To prevent breathing of the unit through the junction betweenthe envelope and the base of the lamp and the porous, conventional basing cement therebetween as a result of internal filamentaryheat which produces pressure differentials between the inside of the sealed package unitand the outside atmosphere, a band of sealing varnish having heat resistant, non-volatile, and plastic characteristics is employed to cover the spaces and irregularities between the base and bulb. The sealing varnishes employed for this purpose contain very plastic heat resistant resins and solvents having a high boiling point and require a drying and curin period of long duration. The present method of curing the varnish sealing band comprises packing the freshly coated.

lamps base up in trays andstoring 'themfor about sixdays to dry in air. During this period, if the varnish is thin or applied more heavily than is required, or if the lamp reclinesat an angle from the vertical, the varnish will run on to the lamp bulb or envelope. The lamps are then baked in ovens having temperatures gradually increasing from 80 to 155 0. During baking, the sealing varnish thins and then further tends to run. The varnish which has run on to the bulb is generally removed by hand scraping or other similar means. This-is an expensive and tedious task. 7

Hence it has been found advantageous, according to my invention, to rotate the coated lamps while slowly baking out the varnish solvent in the varnish sealing band, thereby eliminating the running of the varnish on to the bulb. The coated lamps are fed base first into a slowly ro tating tubular oven externally heated as desired in gradually increasing increments of temperature along its length. Due to the base diameter being smaller than the bulb diameter, the oven rotation causes the lamps to rotate and to roll forward along the bottom of the oven wall. A series of these ovens interconnected by gravitational chutes can bearranged to meet-any re-' duired production rate and total baking time per lamp. L

2 time per lamp.

In its general aspect, the present invention has the objective of overcoming the afore-mentioned disadvantages of the prior art method and'apparatus for curing the varnish seal between the base and envelope of miniature headlight lampsl Specifically,f an object of the present invention is elimination of the runnng of the sealing varnish on to the lamp envelope during the baking process,and make possible the completion of processing of the lamp without a time delay.

Another and specific object is the elimination of the hand scraping of lamp envelopes to remove the excess sealingvarnish therefrom. j An additional o'bject is to rotate the lamps while slowly baking out the varnish solvent in the sealing band to prevent the running of the varnish on to the bulb.

A further object is to providea slowly rotatable tubular oven for curing the sealing band; between the envelope and the base of incandescentlamps employed in a sealed package unit.

An additional object is'a series of tubular ovens interconnected by gravitational chutes H and heated by external means in a gradually increas ing temperature gradient along its length, which can be arranged to ,meet any required production rate or totalbaking time per lamp. A still further object is ,a tubular bakingoven which eliminates excessive handling and storing and appreciably shortens the required baking time. g j

Other objects of the invention will appear to those skilled in the artto which it appertains as the description thereof proceeds, both by direct recitation and by implication from the context.

Referring. to the accompanying drawings in which like numerals of reference indicate similar parts throughout theseveral views:

' Fig. :1 is a side elevational view, partially in section, of a rotatable inclinable. tubular oven. embodying my invention for curing the sealing bands between envelopes and bases of miniature incandescent lamps for sealed package units;

Fig. 2 is a sectional view of the-oven on the line II-II'of Fig. 1,111 the direction of the ar rows; 1

Fig. 3 is a sectional view on the line III-III of Fig. 1, in the direction of the arrows;

Fig. 4 is a side elevational view of a series'oftubular ovens, similar tothe oven of Fig. 1, interconnected by gravitational chutes and arranged to satisfy a given production rate ortotal baking Fig. 5 is an elevational View of a miniature incandescent lamp as employed in a sealed package unit.

Fig. 6 is an elevational view of a sealed ackage unit employing a miniature lamp, as illustrated in Fig. 5.

Referring to the drawing, and particularly to Fig. l in detail, a rotatable inclinable tubular oven embodying my invention is designated by the reference numeral I0. This oven I0, suitably a five or six inch iron pipe of desired length, is supported on a frame I2 on its rearward or entrance end by means of a rotating mechanism I 4 between the frame I2 and said oven, and on its forward or exit end by an elevator mechanism I6 between said frame I2 and said oven. The oven is heated in a gradually increasing temperature along its length by a gas burner system or heating system I8 juxtaposed between the rotating mechanism I4 and the elevator mechanism I6 on frame I2. Suitable vent holes II in oven I and an air blast I2 at one end may be provided to remove vapors from the baking operation.

Frame The frame I2 consists of a vertical rear pillar or pedestal and a vertical forward pillar or pedestal 22, shorter than pedestal 20, interconnected near their lower extremities by a platform 24 and secured to the floor by means of brackets 26. As shown in Fig. 2, rear pedestal 20 has two parallel vertical channel bars 21 and 28 joined together at their tops by a horizontal top channel bar 29. The forward pedestal, as shown in Fig. 3, comprises two vertical channel bars 30 and 3 I, similar to bars 21 and 28, connected by a horizontal top plate 32 suitably of greater depth than member 29.

Rotating Mechanism The rotating mechanism I4, as shown in Figs. 1 and 2, has a body or housing 34 secured to top channel bar 29, as by a bolt 35 and nut 36. This housing has roller arms 31 and 38 projecting from its side portions, as shown particularly in Fig. 2, for aflixing rotatable rear guide and oven support rollers 39 and 40 on their respective upper extremities.

As shown in Fig. 1, the arm 31 projects from the rear portion of housing 34 and the arm 38 from the forward portion of said housing in spaced relationship thereon, so that roller 39 on arm 31 rotates within a circular channel 42 provided on the periphery of oven I0 and roller 40 on arm 38 rotates against the forward flange of said channel, thereby preventing longitudinal movement of oven I0 during rotation thereof.

Housing 34 further has a longitudinal shaft hole 44 and a bushing 46 therein, wherein a shaft 48 rotates and projects therefrom on both sides of housing 34. The projecting portions of shaft 48 are of an appropriate smaller diameter than. the central portion.

On the rearward end of shaft 48 a driver spur gear 50 is secured, as by pinning. On the forward end is secured a sprocket wheel 52. Both gear 50 and sprocket wheel 52 abut housing 34, thereby locking shaft 48 within housing 34 and preventing any longitudinal movement thereof. A driven spur gear 54 of suitable diameter larger than spur gear 50 is aflixed as by welding to the periphery of oven I0 in toothwise engagement with spur gear 50. A chain 56 connects sprocket wheel 52 with another sprocket wheel (not shown) on the drive shaft of gear reduction mechanism 51 driven by a motor 58 on frame platform 24.

Elevator mechanism The elevator mechanism I6, as shown in Figs. 1 and 3, has a height adjustment screw 60 with a handle wheel 62 depending from top plate 32 of forward pillar 22 between the channel bars 30 and 3| of said pillar 22, a shoulder 64 on the top surface of plate 32 and a threaded upper portion 66. Shoulder 64 and handle 62 prevent vertical travel of the screw 60 but permit slidable rotation thereof in a lining 68 (Fig. 1) secured in a vertical hole 10 provided in plate 32. This elevator housing or body 12, as shown in Fig. 3, has its lining 68 suitably threaded so that it travels up and down as the vertically stationary screw 60 is turned, A vertical guide pin slot 14 is machined into the forward face of housing 12. This slot is slidable about the upper portion of a pin guide 16 having its suitably smaller diameter and threaded lower portion extending through top plate 32 and secured thereat by a nut 18.

As shown particularly in Fig. 3, the elevator housing I2 is provided with roller arms and 82 arranged like the arms 31 and 38 of rotating mechanism housing 34. These arms 80 and 82 have forward guide and oven support rollers 84 and 86 rotatably affixed to their respective upper portions. Roller 86 on arm 82 rotates within an annular channel 88, similar to channel 42, secured as by welding to the periphery of the oven I0. Roller 84 on arm 80 in turn rotates against the rearward flange of channel 88. Thus longitudinal generally horizontal motion of the oven I0 is further prevented by the coordinated looking action of the rollers 84 and 86 in and against the channel 88.

Heating system The heating system I8, as shown in Fig. 1, has

a gas line 90 affixed by means of an adjustable bracket 92 to a stanchion 94 on frame platform 24, for supplying, from a T 86, gas for two pipelike burners 98 and I09. These burners are maintained parallel to oven I0 by means of adjustable bracket 92 and a flexible lower portion I02 of gas line 90. The gas flow to burner 98 and I00 and the resultant temperature gradient of approximately 80 to C. along the length of oven I0 are controlled by a valve I04 and a valve I06 in the connecting lines I08 and H0 il'espectively between .T 86 and burners 98 and An inclined gravitational entrance chute I I2 is provided near the rearward portion of oven I0 for delivering miniature incandescent lamps, such as lamp 4 shown in Fig. 5, bulb end first to the oven I0. This lamp II4 comprises an envelope or bulb I I6 having an outside diameter, for example, of 1% inches, a mount H8 sealed therein, a.v base I20 having a shell diameter, for example, of inch, aflixed to the envelope by an appropriate cement and a band I22 of sealing varnish, such as Dow Corning Silicon 996, between the base I20 and the bulb II6. Silicon 996 is the trade name for a solution of silicon resin in a solvent, toluol, having a viscosity of 5 to 10 min. at 29 to 30 C.

. A conveyor I24 as shown in Fig. 1 may be provided at the forward or delivery end of oven III for transporting the lamps H4 after curing to the packing department for cleaning, marking, packing and shipment to the manufacturer of sealed package units I25 such as shown in Fig. 6. This conveyor I2 4- is mountedon a conveyor pedestal I26, forward of pedestal I22, by means of bolts I21 and, I28, adjustablein a. vertical slot I30 in as in Fig. 1.

. It will be understood that the forward rate of longitudinal travel of the lamps I I4 in the revolvable and reclinable oven I and hence the total curin time given lamps H4 in the oven I0 depends on the speed of rotation ,of oven I0 in revolutions per minute (readily adjustable to any desired speed by gear box 51), the length of oven I0, the ratio of bulb diameter to base shell diameter, the surface friction to the base shell diameter inside oven I0, and the inclination of the forward end of oven I 0 (adjustable by means of elevator mechanism I6). For a given length of oven I0 and speed of rotation, if the forward end of oven I0 is inclined upwardly, a given amount, a longer curing time results due to the increased surface friction inside oven I0. Similarly, as the forward portion of oven I0 is inclined downwardly, a shorter curing time for lamp II4 results.

Series of ovens Further, for example, if a longer oven is required and floor space is limited, a series of ovens, such as I38, I 40 and I 42, shown in Fig. 4, aligned one below the other and interconnected by gravitational chutes I44 and I46 of semicircular vertical cross section may be employed. A driven gear I48 on oven I42, similar to spur gear 50 on oven I0, engages a spur gear I50 on oven I40. In turn, gear I50 engages a further spur gear I52 on oven I38. rotate counter to the rotation of the gear I52 on oven I38 and gear I48 onoven I42. The retating mechanism I4 on the rearward portion of oven I42 and the elevator mechanism I6 on the forward end of oven I42 (not shown) function A heating system similar to heating system I8 of Fig. 1 with-additional burners I54 and I56 for oven I38 and I58 and I60 for even I40 similar to burners 98 and I00 of Fig. l, for oven I42 is employed. Arms 80 and 82 of elevator mechanism are extended vertically upward and two additional pairs of rollers ,(not shown) similar to rollers 84 and 86 are employed to support the forward ends of ovens I 38 and I40. j

Operation According to my invention, each lamp I I4 is baked in the oven I0 approximately 45 to 50 minutes at a temperature ranging from 80 to 155C. If the desired production rate of cured lamps is, for example, 150 per hour, an oven I0 about 30 ft. long, rotating at approximately revolutions per minute, and having no inclination of the forward end, may be employed. Lamps II4 fed bya chute II2 into said oven at the rate of one every 24 seconds advance of an inch per second forwardly in the oven I0 and are heated by burners 98 and I00 gradually from 80 to 155 C. Thus, each lamp II 4 delivered at the rearward livered at the forward end of oven I0 onto con Gear I58 on oven I40 and oven I40 end by chute II2 advances 24 sec. or'approximately 3 inches into the oven I0 before the next lamp is delivered by chute II2. Each delivere l amp is heated at therdesired-temperature nsef a md'of;

, or 3000" sash s 50 minutes flbefore being (19- veyorI24. g v r Further, according to my invention, if the desired production rate of cured lamps II4 is, for

example, 1500 per hour, a series .of 3 ovens, such as I38, I40 and I42, as shown in Fig. 4, each long and rotatingat approximately 50 revolutions per minute might be employed. Lamps II4 are fed by chute I I2 into the. upper oven I38 at the rate of one lamp every 2.5 seconds and advance down oven I38 at the rate of 1.2" per second. Chutes I 44 and I46 transfer the lamps in the matter of a second to oven I40 and I42 respectively. Thus the lamps I I4 are given a curing time of v or 3080 seconds, 51% minutes).

Thus it will be seen from the foregoing description that the rotatable and inclinable oven.

curing process and the scrapingof lamp envelopes,

and bases, to remove excesssealing varnish therefrom. The lamps II,4 are rotated-baseend first; slowly in oven I0 thereby travellingvlongitudinally forward in oven' I0. Simultaneously the varnish solvent in the sealing band I22 is baked out to prevent the running of the varnish onto the bulb II6. Further, a series of rotatable and inclinable tubular ovens, such as ovens I38, I40 and I42 of Fig. 4 interconnected by gravitational chutes I44 and I46 and heated by burners such as 98 and I00, I54 and I56 and I58 and I60 in a gradually increasing temperature gradient along their respective lengths may be arranged to meet any required production rate. or total baking time per lamp.

Althougha preferred embodiment of my invention has been disclosed, it will be understood that modifications may be made within the spirit and scope of the appended claims.

I claim:

1. Apparatus for curing a varnish sealing band between the bulb and the base of miniature incandescent lamps comprising a rotatable inclinable tubular oven, having forward and rear annular roller channels and an oven spur gear adjacent said rear roller channel, a frame having vertical rear and forward pedestals interconnected by a platform, an oven rotating mechanism on the rear pedestal of said frame between said oven and said rear pedestal, said mechanism comprising a housing secured to said rear pedestal, roller arms projecting from the side portions of said housing, guide oven support rollers on said arms for engagement with the rear channel of said oven to prevent longitudinal movement thereof, a driver shaft within said housing,

a spur gear on the rearward end of said shaft rotatably secured but vertically fixed to the upper portions of said forward pedestal, an elevator housing in threadable engagement with the upper end of said screw and keyed to said forward pedestal, roller arms projecting from the side portions of said elevator housing, rollers on said arms for engagement with the forward channel of said oven to further prevent longitudinal movement thereof, and manual means on the lower end of said screw for'rotating said screw, and a heatlng system on said frame between said rotating mechanism and said elevator mechanism for heating said oven in a gradually increasing temperature gradient along its length.

2. Apparatus for curing a varnish sealing band between the bulb and the base of miniature incandescent lamps comprising a series of rotatable and inclinable tubular ovens aligned one below the other and having oven spur gears on the rear portions thereof for intermeshing engagement with each other, the bottom oven also having forward and rear annular roller channels, gravitational chutes for interconnecting said ovens, a frame having vertical rear and forward pedestals interconnected by a platform, an oven rotating mechanism on the rear pedestal of said frame between said bottom oven and said rear pedestal, said mechanism comprising a housing secured to said rear pedestal, roller arms projecting from the side portions of said housing, guide oven support rollers on said arms for engagement with the rear channel of said bottom oven to prevent longitudinal movement thereof, a driver shaft within said housing, a spur gear on the rearward end of said shaft for engagement with said bottom oven gear, a sprocket wheel on the forward end of said shaft and means for adjustably rotating said sprocket wheel and said shaft, an oven elevator mechanism on the forward pedestal of said frame between said oven and said forward pedestal, said elevator mechanism having a height adjustment screw rotatably secured but vertically fixed to the upper portions of said forward pedestal, an elevator housing in threadable engagement with the upper end of said screw and'keyed to said forward pedestal, roller arms projecting from the side portions of said elevator housing, rollers on said arms for engagement with the forward channel of said bottom oven to further prevent longitudinal movement thereof, and manual means on the lower end of said screw for rotating said screw, and a heating system on said frame between said rotating mechanism and said elevator mechanism and extending beneath and along each of said aligned ovens for heating said ovens in a gradually increasing temperature gradient along their combined length.

ALBERT W. HOLZER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,064,223 Wallos June 10, 1913 1,420,144 Pye June 20, 1922 FOREIGN PATENTS Number Country Date 87,936 Switzerland Jan. 17, 1921 

